Sulfur containing organosilicon compounds

ABSTRACT

1. A PROCESS OF PREPARIG A COMPOUND HAVING THE FORMULA Z-ALK-SN-ALK-Z, IN WHICH Z IS -SI(-R1)2-R2, -SI(-R2)2-R1, OR -SI(-R2)3 WHEREIN R1 IS ALKYL OF 1 TO 4 CARBON ATOMS OR PHENYL AND R2 IS ALKOXY OF 1 TO 8 CARBON ATOMS, CYCLOALKOXY WITH 5 TO 8 CARBON ATOMS OR ALKYLMERCAPTO WITH 1 TO 8 CARBON ATOMS, ALK IS A DIVALENT HYDROCARBON OF 1 TO 18 CARBON ATOMS AND N IS AN INTEGER OF 2 TO 6 COMPRISING REACTING A COMPOUND OF THE FORMULA Z-ALK-HAL WITH A COMPOUND OF THE FORMULA ME2SN WHERE ME IS AMMONIUM, ALKALI METAL OR AN ALKALINE EARTH METAL AND HAL IS A HALOGEN OF ATOMIC WEIGHT 35 TO 127

United States Patent 3,842,111 SULFUR CONTAINING ORGANOSILICON COMPOUNDSEugen Meyer-Simon and Werner Schwarze, Frankfurt,

Friedrich Thurn, Grossauheim, and Rudolf Michel, Somborn, Germany,assignors to Deutsche Goldund Silber-Scheideanstalt vormals Roessler,Frankfurt am Main, Germany No Drawing. Filed Aug. 1, 1972, Ser. No.277,043 Claims priority, application Germany, Aug. 17, 1971,

P 21 41 159.6, P 21 41 160.9; Mar. 14, 1972,

Int. Cl. C07f 7/10, 7/18 US. Cl. 260-448.2 E 33 Claims ABSTRACT OF THEDISCLOSURE Sulfur containing organosilicon compounds are prepared havingthe formula:

where R is alkyl of 1 to 4 carbon atoms or phenyl and R is alkoxy of 1to 8 carbon atoms, cycloalkoxy of 5 to 8 carbon atoms or alkylmercaptoof 1 to 8 carbon atoms, alk is a divalent aliphatic hydrocarbon orunsaturated aliphatic hydrocarbon or a cyclic hydrocarbon containing 1to 18 carbon atoms and n is a whole number from 2 to 6. The compounds ofthe present invention are useful as bonding agent in sulfur vulcanizablerubbers.

The present invention is directed to new sulfur containing organosiliconcompounds which are useful for example as bonding agents in sulfurvulcanizable rubber mixtures reinforced with natural or syntheticsilica. The rubber can be natural rubber or other sulfur vulcanizablerubbers such as butadiene-styrene, butadiene-acrylonitrile,polyisoprene, polybutadiene, ethylene propylene-diene terpolymer andbutyl rubber.

The invention is also concerned with processes for producing the novelcompounds.

The compounds of the invention are also useful as intermediate productsfor producing water repellent agents or oxidation inhibitors or asprotective agents for metal surfaces.

It is known to use 3-mercaptopropyl trimethoxysilane as adhesivepromoters in rubber mixtures. Advantageously, however, in the use ofsuch compounds it is important that they reduce the strength of the rawmixture and considerably raise the tensile strength of the vulcanizateand definitely raise the rebound and shore hardness. On the contrary theprocessing properties of the mixture are disadvantageously influenced,for example the prevulcanization time is greatly reduced. This means areduction of the processing safety. Furthermore, the Defo elasticity isgreatly increased which means an increase in the elastic rubber portionof the raw mixture and has a consequence an increased difiiculty intheir further processing, for example in injection molding.

It is an object of the invention to prepare new sulfur containingorganosilicon compounds which can be used for this purpose withoutrequiring that allowance be made for the above named disadvantages. Onthe one hand they substantially produce the advantages for example of3-mercaptopropyltrimethoxysilane but on the other hand substantiallymore favorably effect the processing properties of the rubber-fillermixture. Furthermore, many of the compounds of the invention, because oftheir simple Patented Oct. 15, 1974 method of production with goodyields and the easy availability of their starting materials, areaccessible in very economical manners. Therefore these compounds areexcellent for industrial duty.

The new compounds have the general formula:

I ZalkS alkZ in which Z is:

and in which R, is an alkyl group of 1 to 4 carbon atoms or phenyl and Ris an alkoxy group with 1 to 8, preferably 1 to 4, carbon atoms, acycloalkoxy group with 5 to 8 carbon atoms or a straight or branchedchain alkylmercapto group with 1 to 8 carbon atoms. All the R and Rgroups can be the same or different. Alk is a divalent hydrocarbon groupwith 1 to 18 carbon atoms. It can be straight or branched chain and canbe a saturated aliphatic hydrocarbon group, an unsaturated aliphatichydrocarbon group or a cyclic hydrocarbon group. Preferably alk has 1 to6, most preferably 2 or 3 carbon atoms and n is a whole number of 2 to6, especially 2, 3 or 4, most preferably 4.

The compounds of the invention are valuable bonding agents (adhesionpromoters) which are added with advantage, for example in vulcanizableor cross linkable rubber mixtures reinforced with fiinely divided lightor white fillers, especially natural or synthetic silica fillers. Therecan also be used other known metaloxides such as magnesium oxide andaluminum oxide, mixtures of oxides and mixed oxides, silicates, e.g.glass, glass fibers, etc. There can also be present carbon black as astrengthening filler.

The new rubber adjuvants improve the mechanical properties of thevulcanizate, especially in static and dynamic stress.

Especially suitable for this purpose are compounds in which the alk isan ethylene or propylene group (trimethylene) and Z is the group where Ris alkoxy of 1 to 4 carbon atoms.

The compounds in which R is alkoxy are preferred to those in which R isan alkyl mercapto group.

The compounds of the type set forth in general are yellow liquids whichcannot be distilled without decomposition. Their viscosities depend uponthe chain length of the alkylene group, is. the viscosity increases withincreasing molecular weight.

Examples of compounds within the invention include 3,3'-bis(trimethoxysilylpropyl) disulfide, 3,3-bis(triethoxysilylpropyl)tetrasulfide, 3,3-bis(trimethoxysilylpropyl) tetrasulfide,2,2-bis(triethoxysilylethyl) tetrasulfide,

3,3-bis (trimethoxysilylpropyl) trisulfide,

3 ,3 '-bis (triethoxysilylpropyl) trisulfide,3,3-bis(tributoxysilylpropyl) disulfide, 3,3'-bis(trimethoxysilylpropyl)hexasulfide, 3,3-bis(trioctoxysilylpropyl) tetrasulfide,3,3-bis(trihexoxysilylpropyl) disulfide,3,3'-bis(tri-2"-ethylhexoxysilylpropy1) trisulfide, 3 ,3 '-bistriisooctoxysilylpropyl) tetrasulfide, 3,3-bis(tri-t-butoxysilylpropyl)disulfide, 2,2'-bis(methoxy diethoxy silyl ethyl) tetrasulfide, 2,2'-bis(tripropoxysilylethyl) pentasulfide, 3,3'-bis(tricyclohexoxysilylpropyl)tetrasulfide, 3,3'-bis(tricyclopentoxysilylpropyl) trisulfide,

2,2'-bis(tri-2"-methylcyclohexoxysilylethyl) tetrasulfide, bis(trimethoxysilylmethyl) tetrasulfide)3,3'-bis(trimethylmercaptosilylpropyl) tetrasulfide, 2,2-bis(triethylmercaptosilylethyl) disulfide, 2,2'-bis(tributylmercaptosilylethyl) trisulfide, 2,2-bis(tri sec.butylmercaptosilylethyl) trisulfide,3,3-bis(trioctylmercaptosilylpropyl) tetrasulfide, 2,2'-bis(trihexylmercaptosilylethyl) hexasulfide,3,3-bis(ethyldipropylmercaptosilylpropyl) tetrasulfide, 3-methoxy ethoxypropoxysilyl 3'-diethoxybutoxysilylpropyltetrasulfide, 2,2-bis(dimethylmethoxysilylethyl) disulfide, 2,2-bis(dimethyl sec.butoxysilylethyl)trisulfide, 3,3'-bis(methyl butylethoxysilylpropyl) tetrasulfide,3,3'-bis(di t-butylmethoxysilylpropyl) tetrasulfide, 2,2'-bis(phenylmethyl methoxysilylethyl) trisulfide, 3,3'-bis(diphenylisopropoxysilylpropyl) tetrasulfide, 3,3-bis(diphenylcyclohexoxysilylpropyl) disulfide, 3,3'-bis(dimethylethylmercaptosilylpropyl) tetrasulfide, 2,2'-bis(methyldimethoxysilylethyl) trisulfide, 2,2'-bis (methylethoxypropoxysilylethyl) tetrasulfide, 3,3'-bis(diethylmethoxysilylpropyl) tetrasulfide, 3,3'-bis(ethyl di-sec.butoxysilylpropyl) disulfide, 3,3-bis(propyl diethoxysilylpropyl)disulfide, 3,3'-bis(butyl dimethoxysilylpropyl) trisulfide,3,3-bis(phenyl dimethoxysilylpropyl) tetrasulfide, 3-phenylethoxybutoxysilyl 3-trimethoxysilylpropyl tetrasulfide, 4,4'-bis(trimethoxysilylbutyl) tetrasulfide, 6, 6-bis triethoxysilylhexyl)tetrasulfide, 12,l2'-bis(triisopropoxysilyl dodecyl) disulfide,18,18-bis(trimethoxysilyloctadecyl) tetrasulfide,l8,18'-bis(tripropoxysilyloctadecenyl) tetrasulfide,4,4'-bis(trimethoxysilyl-buten-Z-yl) tetrasulfide,4,4'-bis(trimethoxysilylcyclohexylene) tetrasulfide, ,5 '-bisdimethoxymethylsilylpentyl trisulfide,3,3-bis(trimethoxysilyl-Z-methylpropyl) tetrasulfide,3,3-bis(dimethoxyphenylsilyl-Z-methylpropyl) disulfide.

The compounds of the invention can be prepared in a simple andeconomical manner by reacting 2 moles of a compound of the formula wherehal is a chlorine, bromine or iodine atom (i.e. halogen of atomic weightto 127) and Z and alk are as defined above, with 1 mole of a compound ofthe formula (III) Me S where Me is ammonium or a metal atom, especiallyan alkali metal atom, e.g. potassium, sodium, rubidium or cesium and nis as defined above. Preferably Me is sodium. The reaction is preferablycarried out in an organic solvent, the product is separated from thehalide material formed and in a given case the organic solvent removed.

Examples of suitable starting compounds within formula are Na S KZSG,Nagse, C5255, K3284, K282, 2 3 4)2 2 02 3, 4)2 4 and especially Na SNa-2S3 and N3284- Other polysulfides which can be used include alkalineearth metal polysulfides, e.g. BaS and Basi The mole ratio of thecompound of formula II to the compound of formula 111 can vary from 2 to1 to 2 to 2. 1

Typical examples of starting materials within formula II are2-chloroethy1 trimethoxysilane, 2-bromoethy1 trimethoxysilane,2-iodoethyl trimethoxy silane, 3-bromopropyl trimethoxysilane,3-chloropropyl trimethoxysilane, 3-iodopropyl trimethoxysilane,3-bromopropyl triethoxysilane, 3-iodopropyl triethoxysilane,

2-bromoethyl tripropoxysilane,

2-iodoethyl tributoxysilane,

2-chloroethyl tri sec.butoxysilane,

3-bron1opropyl tri-t-butoxysilane,

3-iodopropyl triisopropoxysilane,

3-bromopropyl trioctoxysilane,

2-chloroethyl tri-2-ethylhexoxysilane, Z-bromoethyl dimethoxyethoxysilane, 3-iodopropy1 methoxyethoxypropoxysilane, 3-chloropr0pyldimethoxy methylsilane, 3-bromopropyl dimethoxy methylsilane,3-chloropropylmethoxydimethylsilane, 3-bromopropylmethoxydimethylsilane,3-chloropropyldirnethoxymethylmercaptosilane,3-iodopropyldimethoXymethylmercaptosilane, 3-chloropropyl methoxy di(methylmercapto) silane, 3-iodo-propyl methoxy di (methylmercapto)silane, 3-chloropropyl methoxy methyl methylmercapto silane,3-bromopropyl methoxy methyl methylmercapto silane, 3-iodopropyl methoxymethyl methylmercapto silane, Z-chloroethyl trimethylmercaptosilane,3-bromoethyl trimethylmercaptosilane, Z-iodoethyltriethylmercaptosilane,

2-bromoethyl triisopropylmercaptosilane, 3-iodopropyltripropylmercaptosilane, 3-chloropropyl tributylmercaptosilane,2-bromoethyl tri sec. butylmercaptosilane,3-bromopropyltrioctylmercaptosilane, 3-chloropropyl cyclohexoxydimethylsilane, 3-bromopropyl cyclohexoxy dimethylsilane, 4-chlorobutyltrimethoxysilane, 4-bromobutyltrimethoxysilane, 3-chloro-3-methylpropyltrimethoxysilane, 3-bromo-3-methylpropyl trimethoxysilane,3-chloro-3-methylpropyl tripropoxysilane, 3-bromo-3-methylpropyltripropoxysilane, 3-chl0ro-3-ethylpropyldirnethoxy methylsilane,3-bromo-3-ethylpropyldimethoxy methylsilane, 3-chloro-2-methylpropyltrimethoxysilane, 3-bromo-2-methylpropyl trimethoxysilane,3-chloro-2-methylpropyl dimethoxy phenylsilane, 3-bromo-2-methylpropyldimethoxy phenylsilane, 3-chloro-cyclohexyl-trimethoxysilane,3-iodocyclohexyltrimethoxysilane, 3-chlorocyclohexy1 dimethoxypropylmercaptosilane, 3-iodocyclohexyl-dimethoxy propylmercaptosilane,12-chlorododecyl trimethoxysilane,

l2-iodododecyl trimethoxysilane,

12-chlorododecyl triethoxysilane,

12-iodododecyl triethoxysilane,

18-chlorooctadecyl trimethoxysilane, 18-bromooctadecyl trimethoxysilane,l8-chlorooctadecyl methoxydimethylsilane, 18-bromooctadecylmethoxydimethylsilane, 2-chloro-2-methylethyl-trimethoxysilane,2-iodo-2-methylethyl-trimethoxysilane,2-chloro-2-methylethyl-triethoxysilane,2-iodo-2-111ethylethyltriethoxysilane,2-chloro-2-methylethyl-tripropoxysilane,2-iodo-2-methylethyl-tripropoxysilane,2-chloro-Z-methylethyl-trioctyloxysilane, and2-iodo-2-methy1ethyl-trioctyloxysilane.

Of the sulfur containing organosilicon compounds within formula Ipreferably there are prepared 3,3- bis (trimethoxy or triethoxysilylpropyl) sulfides, specifically di, tri and tetrasulfides. Othercompounds of the invention employed with good success include the2,2'bis(trimethoxy, triethoXy, tri-methylethoxy, tributoxy, etc.silylethyl) sulfides, preferably the di, tri and tetrasulfides, as wellas the 3,3'-bis (trimethoxy or dimethoxy methylsilylisobutyl) sulfides,especially the di, tri and tetrasulfides, and also the 4,4'-bis(trimethoxy or dimethoxyphenyl or dimethoxymethylmercapto, ormethoxydimethyl silylbutyl) sulfides, especially the di, tri andtetrasulfides.

The compounds of formula II are preferably chloro or bromo compounds andalk is preferably di, tri or tetra methylene, in a given case loweralkyl substituted derivatives thereof, especially methyl substituted.

The temperature at which the reaction is carried out between thecompound of formula II and the compound of formula III is not critical.The reaction can take place at room temperature as Well as temperaturesbelow room temperature. In order to increase the speed of reaction,however, it is generally advantageous to work at elevated temperaturesup to the boiling point of the solvent used in a given case. Since thestarting materials are liquid the reaction can take place in the absenceof a solvent. Advantageously, however, there is used an inert organicsolvent, most preferably volatile organic solvent, which is able topartially or more preferably completely dissolve the compound of formulaIII. Desirably the solvent does not dissolve the metal halide formed.Solvents include for example aliphatic and cycloaliphatic alcohols suchas methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol,butyl alcohol, sec. butyl alcohol, t-butyl alcohol, amyl alcohol, hexylalcohol, octyl alcohol, 2-ethylhexyl alcohol, isooctyl alcohol,cyclohexanol, cyclopentanol, methylcyclohexanol. Preferably there isused an alcohol which corresponds to the structure and number of carbonatoms in the hydrocarbonoxy group bonded to the silicon, for exampleethyl alcohol with ethoxy group containing silanes. There also can beused ketones containing up to eight carbon atoms such as acetone, methylethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methylbutyl ketone, diethyl ketone, methyl hexyl ketone and cyclohexanone.There also can be used cyclic ethers such as tetrahydrofurane, dioxane,dioxolane and other oxygen containing compounds. The preferred solventsare methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol,cyclohexyl alcohol and acetone.

Furthermore it has been found advantageous to carry out the reactionwith the exclusion of water and/or the exclusion of air. As inert gasesthere can be used noble gases, e.g. argon, neon and helium, or nitrogen.Both precautions effect a reduction in side reactions.

In carrying out the process of the invention it is more preferable tofirst dissolve the compound of formula III partially or completely in aninert organic solvent. The solvent is advantageously selected so thatundesired ester interchanges of the silicon atom are excluded. To thissolution there is added the starting material of formula II, in a givencase likewise dissolved in a solvent. After the end of the reaction thesalt (metal halide) separated out is filtered off and the organicsolvent, in a given case under reduced pressure, is removed bydistillation. The end product cannot be distilled without decomposition.It remains behind in the distillation sump. It can be used directlywithout purification.

It was completely surprising that the process set forth above could beused with starting compounds which have the halogen atom in the betaposition. It is known from Organometallic Reviews A 6 (1970) 2, pages153-207, that halogen atoms, for example chlorine or bromine atoms whichare found in the beta position tothe silicon atom, are unstable. Forthis reason substitution reactions in the presence of specific solvents,for example alcoholic alkalis, as shodium methylate solution, arepractically impossible since a splitting of the Si-C-bond takes placequickly. Thus, for example, it is known that organosilicon compounds, as,B-chloroethyltriethylsilane are substantially less stable to alkalimetal hydroxide or alkoxide solutions than are the corresponding alphaor gamma isomers. For example B-chloroethyltriethylsilane is quicklydecomposed with the quantitative formation of ethylene and the settingfree of chloride ions when using aqueous or alcoholic alkali metalhydroxide or alkoxide solutions. The process of the invention on thecontrary can also be carried out in the substitution reactions withaddition of organosilicon compounds which contain a halogen atom in betaposition to the silicon atom. In view of this state of the art it wasunexpected and surprising that contrary to the expected splitting asubstitution occurs.

The reaction process can also be carried out continuously. I

/II] a suitable working of the process both reaction partners arepreheated separately in the liquid phase. In addition the sulfide offormula III is brought into solution, for example in alcoholic solution.

Then the reaction partners are fed into a heatable reaction vessel andallowed to react with each other while flowing through the vessel. It isadvantageous for this purpose to use a tubular reaction vessel providedwith a heating jacket and filled with packing, for example Raschig ringsor similar known packing.

The reaction temperature is usually between about 30 and 120 C.,especially between about 60 and C., preferably at about the boilingpoint of the solvent. As previously pointed out the temperature can bebelow 30 C. and by the addition of higher boiling solvents or by Workingunder superatmospheric pressure in a given case can be above C.

The mixture of the resulting compounds then flows through a coolingaggregate whereupon the filtering off of the solid constituents takesplace, for example over a Seitz filter, and the rectification in avacuum for the removal of solvent.

There can be produced in another simple manner compounds of formula I inwhich n is 3 to 6 by reacting (a) 2 moles of a compound of the formulaIV ZalkSH, in which Z and alk are as defined above with 1 mole of acompound of the formula V S Hal in which Hal is a chlorine or bromineatom (i.e. a halogen of atomic weight 35 to 80), and m is a whole numberof 1 to 4. Compounds within formula V include SCl SBr S CI SrBr S3012,S2BI'2, S4C12 and S4BI'2.

Compounds within formula IV are Z-mercaptoethyl trimethoxysilane,3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane,Z-mercaptoethyl tripropoxysilane, Z-mercaptoethyl tri sec. butoxysilane,3-mercaptopropyl tri-t-butoxysilane, 3-mercaptopropyltriisopropoxysilane, 3-mercaptopropyl trioctoxysilane, 2-mercaptoethyltri-2'-ethylhexoxysilane, 2-mercaptoethy1 dimethoxy eth oxysilane,3-mercaptopropyl methoxyethoxypropoxysilane, S-mercaptopropyl dimethoxymethylsilane, 3-mercaptopropyl methoxy dimethylsilane, 3-mercaptopropyldimethoxy methylmercaptosilane, 3-mercaptopropyl methoxydi(methylmercapto) silane, 3-mercaptopropyl methoxy methylmethylmercapto silane, Z-mercaptoethyl trimethylmercaptosilane,Z-mercaptoethyl triethylmercaptosilane, 2-mercaptoethyltriisopropylmercapto silane, B-mercaptopropyl triisopropylmercaptosilane, 3-mercaptopropyl tributylmercapto silane, Z-mercaptoethyltri-Secbutylmercaptosilane, 3-mercaptopropyl trioctylmercaptosilane, 3-mercaptopropyl cyclohexoxy dimethyl silane, 4-mercaptobutyltrimethoxysilane, 3-mercapto-3-methylpropyltrimethoxysilane,3-mercapto-3-methylpropyl-tripropoxysilane,3-mercapto-3-ethylpropyl-dimethoxy methylsilane, 3-mercapto 2methylpropyl trimethoxysilane, 3-mercapto-2- methylpropyl dimethoxyphenylsilane, 3-mercaptocyclohexyl-trimethoxysilane,3-mercaptocyclohexyl dimethoxy propylmercaptosilane, IZ-mercaptododecyltrimethoxy silane, 12-mercaptododecyl triethoxy silane,l8-mercaptooctadecyl trimethoxysilane, 18-mercaptooctadecylmethoxydimethylsilane, 2-mercapto 2 methylethyl-trimethoxysilane,2-mercapto-2-methylethyl-triethoxysilane, 2-mercapto-2-methylethyl-tripropoxysilane, and Z-mercapto-2-methylethyl-trioctoxysilane.

Preferably the reaction is carried out in the presenc of an organicsolvent and the hydrogen halide formed, as well as in a given case thesolvent, removed.

Another procedure is (b) to oxidize a compound of formula IV, preferablyat elevated temperature, e.g. 60 to C. to a compound of formula I inwhich n is 2,

preferably in the presence of an organic solvent and in a given caseunreacted starting compounds and solvent are removed from the reactionmixture.

It is recommended to carry out the reaction according to procedure (a)at room temperature. However, temperatures above and below this can beused, e.g. to 80 C. By employing the higher temperatures a strongreaction must be reckoned with.

As stated it is advantageous to carry out the reaction in the presenceof inert solvents. As such there can be used ethers, e.g. diethyl ether,dimethyl ether, dipropyl ether, methyl butyl ether, tetrahydrofurane,dioxane, aromatic hydrocarbons, for example benzene, toluene and xylene.Petroleum ether is a preferred solvent.

As in the previously described reactions it is preferred to carry outthe reaction with the exclusion of water and/ or with an inertatmosphere. For example, the reaction is carried out under nitrogen.This procedure avoids the formation of byproducts which would reduce theyield.

In carrying out process (a) one proceeds suitably by diluting thecompound of formula IV for example with petroleum ether and then addsthe compound V likewise diluted with petroleum ether. During thereaction suitably there is led through the mixture an inert gas,especially nitrogen. Leading through of the inert gas also takes placeduring the subsequent after reaction which should be held at the boilingtemperature. The after reaction should take place until no more hydrogenhalide gas escapes. After the end of the reaction the organic solvent isremoved under reduced pressure. The compounds of the invention obtainedby the process cannot be distilled without decomposition. They remainbehind in the distillation sump.

In carrying out the process according to process (b) there can be usedthe oxidation agents known to oxidize mercaptans to disulfide set forthin Houben-Weyl Methoden der Organischer Chemie, 4th edition, 1955 Vol.9, pages 59 to 65, the entire disclosure of which is incorporated byreference. Thus there can be used oxygen, chlorine, halogen of atomicweight 35 to 127 (i.e. iodine or bromine), nitric oxide (NO), sulfurylchloride (SO CI For maximum yield the oxidizing agent should be used inat least the stoichiometric amount. Preferably there are employedcompounds of the formula VI R SOR most preferably in excess. In formulaVI R and R are the same or difierent and are alkyl of 1 to 6 carbonatoms, preferably methyl. Examples of such compounds include dimethylsulfoxide, diethyl sulfoxide, dipropyl sulfoxide, dibutyl sulfoxide,diamyl sulfoxide, dihexyl sulfoxide, diisopropyl sulfoxide, di sec.butyl sulfoxide, methyl ethyl sulfoxide, methyl hexyl sulfoxide andethyl propyl sulfoxide. The oxidation agent must be added under suchconditions that a hydrolysis of bond between the silicon atom and R doesnot take place. The reaction takes place preferably at temperaturesabove room temperature, although room temperature can be used. Forexample in using dialkyl sulfoxides, especially dimethyl sulfoxide, atemperature range of 0 to 120 C. is preferred.

This process also can be carried out in the presence of an organicsolvent. For example there can be used aromatic hydrocarbon such asxylene, toluene and benzene. According to an especially preferredvariant an excess of the dialkyl sulfoxide is used which can thenfunction simultaneously as the solvent.

It is also recommended in this variant to work in an inert gasatmosphere. For example nitrogen can be led through the reactionsolution whereby simultaneously the byproducts of formula VII R SR canbe removed. This can be converted again to starting compound VI bycatalytic air oxidation which can again be used in the process.

The water formed besides in the reaction can remain in the reactionsolution because it only effects a partial and therefore non disturbinghydrolysis of compounds produced. If desired it can be removed by anentraining distillation with toluene.

After the end of the reaction which can last about 5 to 24 hours thestarting materials are removed by distillation which also can take placeunder reduced pressure. The compounds of the invention, as alreadymentioned, remain behind in the distillation sump. A purification is notnecessary.

Unless otherwise indicated all parts and percentages are by weight.

Example 1 There were gradually introduced into a boiling solution of 0.5mole of Na S in 500 ml. of water free methyl alcohol 1 mole of3-chloropropyl trimethoxysilane. After the end of the reaction theseparated salt was filtered off and the filtrate freed from the solventin a vacuum. There were obtained 171 grams (87.5% of theory) of thecompound 3,3-bis(trimethoxysilylpropyl)disulfide of the formula Zi )32)3 2 2)2' 3)3 Analytic values.Calculated: C, 36.89; H, 7.74; Si,

14.37; S, 16.41. Found: C, 36.20; H, 7.48; Si, 13.76; S,

Example 2 There were gradually added to a boiling solution of 0.5 moleof Na S in 500 ml. of waterfree ethanol 1 mole of3-chloropropyl-triethoxysilane. After the end of the reaction theseparated salt was removed by filtration and the filtrate freed from thesolvent in a vacuum. There were obtained 2 63 grams (95.8% of theory) ofthe compound 3,3-bis(triethoxysilyl-propyl) tetrasulfide of the formulaAnalytical values.--Calculated: C, 40.11; H, 7.84; Si, 10.42; S, 23.79.Found: C, 40.0; H, 7.78; Si, 10.48; S, 22.98.

Example 3 There were gradually added to a boiling solution of 2 moles ofNa S in 2000 ml. of water free methanol 4 moles of 3-chloropropyltrimethoxysilane. After the end of the reaction the separated salt wasfiltered off and the solvent removed in a vacuum. There were obtained859 grams (94.1% of theory of the compound3,3'-bis(trimethoxysilylpropyl) tetrasulfide of the formula Analyticalvalues.Calculated: C, 31.69; H, 6.65; Si, 12.35; S, 28.20. Found: C,31.20; H, 6.43; Si, 12.40; S, 27.35.

Example 4 There were gradually added to a solution of 0.5 mole of Na Sin 500 ml. water free ethanol at 50 C. 1 mole of2-chloroethyltriethoxysilane. After the end of the reaction theseparated salt was filtered off and the filtrate freed of the solvent inthe vacuum. There were obtained 226.5 grams (88.7% of theory of thecompound 2,2'-bis (triethoxysilylethyl)tetrasulfide of the formulaAnalytical values.--Calculated: C, 37.61; H, 7.49; Si, 10.99; S, 25.10.Found: C, 37.12; H, 7.32; Si, 11.21; S, 24.38.

Example 5 C. The reaction time in the reaction was regulated (as flowthrough time) at about 15 minutes.

The reaction mixture passed through the after reactor during minutes atwhich time the final temperature was 70 C. After the following coolingin a heat exchanger to about room temperature the precipitated solidsodium chloride was separated off with a filtering device and the ethylalcohol distilled off in a vacuum at about 50 to 60 C. There wasrecovered the almost pure silyl compound.

The yield of 3,3-bis (triethoxysilylpropyl)-tetrasulfide amounted to 95%of the theory.

Example 6 In the same apparatus as in example 5 and under the sameconditions 3-bromopropyltriethoxysilane and dipotassium trisulfide (K 8in the molar ratio of 2 to 1 trisulfide.

Instead of the triethoxysilanes used in examples 5 and 6 there also canbe used as starting materials with advantage the trimethoxysilanes aswell as the tripropoxy and analogous higher alkoxysilanes with up to 8carbon atoms as well as mixed alkyl, cycloalkyl, phenyl alkoxy silanes,etc.

Example 7 A solution of 0.5 mole of (CH O) Si(CH SH in 300 ml. ofpetroleum ether (B.P. 50 to 70 C.) gradually were treated at roomtemperature and while leading nitrogen through the reaction solutionwith a solution of 0.25 mole of SO1 in 100 ml. of petroleum ether (B.P.50 to 70 C.). After end of the addition of the SCSl the mixture washeated to boiling at reflux with the passing through of nitrogen untilHCl development no longer took place (about 90 minutes). After thedistillative removal of the organic solvent there remained 106 grams(100% of theory of the compound of the formula as the distillation sump.

Analytical values.--Calculated: C, 34.09; H, 7.15; Si, 13.29; S, 22.75.Found: C, 33.97; H, 7.03; Si, 12.94; S, 23.08.

Example 8 A solution of 0.5 mole of (C H O) Si(CH SH in 300 ml. ofpetroleum ether (B.P. 50 to 70 C.) at room temperature and with thepassing of nitrogen through the reaction solution was treated graduallywith a solution of 0.25 mole of S Cl in 100 ml. of petroleum ether(B.P.50 to 70 C.) After end of the addition the mixture was heated toboiling at reflux while passing nitrogen through until no more HCldevelopment took place (about 90 minutes). After the distillativeremoval of the organic solvent there remained 134.6 grams (100% oftheory) of the compound of the formula as the distillation sump.

Analytical values.Calculated: C, 40.11; H, 7.84; Si, 10.42; S, 23.79.Found: C, 40.25; H, 7.80; Si, 10.43; S, 23.09.

Example 9 0.5 mole of (CH O) Si(CH SH and 500 ml. of dimethyl sulfoxidewere heated at 100 C. for 18 hours while passing nitrogen through thereaction solution. Finally excess dimethyl sulfoxide and3-mercaptopropyl-trimethoxysilane were removed by distillation in avacuum. In the distillation sump there remained 76 grams (77.5% oftheory) of the compound of the formula Analytical value.Calculated: C,36.89; H, 7.74; Si, 14.37; S, 16.41. Found: C, 36.36; H, 7.64; Si,14.50; S, 16.11.

10 Example 10 0.5 mole of (C H O) Si(CH SH and 500 ml. of dimethylsulfoxide were heated at C. for 24 hours while passing nitrogen throughthe reaction solution. After this time the reaction was practicallycompleted which was evidenced by the only very weakly noticeable odor ofthe last traces of dimethyl sulfide. Finally excess dimethyl sulfoxideand 3-mercaptopropyl tri-n-butoxysilane were removed by distillation ina vacuum. In the distillation sump there remained 121 grams (72% oftheory) of the compound of the formula 1. A process of preparing acompound having the formula Zalk-S -alkZ, in which Z is wherein R isalkyl of 1 to 4 carbon atoms or phenyl and R is alkoxy of 1 to 8 carbonatoms, cycloalkoxy with 5 to 8 carbon atoms or alkylmercapto with 1 to 8carbon atoms, alk is a divalent hydrocarbon of 1 to 18 carbon atoms andn is an integer of 2 to 6 comprising reacting a compound of the formulaZalkhal with a compound of the formula Me S where Me is ammonium, alkalimetal or an alkaline earth metal and hal is a halogen of atomic weight35 to 127.

2. A process according to claim 1 wherein M0 is ammonium, sodium orpotassium.

3. A process according to claim 2 wherein Z is (3).

4. A process according to claim 3 wherein all R groups are alkoxy of 1to 4 carbon atoms.

5. A process according to claim 2 which is carried out in an organicsolvent and the reaction product is separated from metal halide formedand from the organic solvent.

6. A process according to claim 5 which is carried out in thesubstantial absence of water and air.

7. A process according to claim 1 which is carried out continuously.

8. A process according to claim 5 which is carried out continuously.

9. A process of preparing a compound having the formula Zalk--S AlkZ, inwhich Z is wherein R is alkyl of 1 to 4 carbon atoms or phenyl and R isalkoxy of 1 to 8 carbon atoms, cycloalkoxy with 5 to 8 carbon atoms oralkylmercapto with 1 to 8 carbon atoms, alk is a divalent hydrocarbon of1 to 18 carbon atoms and n is an integer of 3 to 6 comprising reacting acompound of the formula ZalkSH with a compound of the formula S Hal inwhich m is an integer of 1 to 4 and Hal is a halogen of atomic weight 35to 80.

10. A process according to claim 9 carried out in an organic solvent atan elevated temperature.

11. A process according to claim 9 including the steps of removing thehydrogen halide formed and the solvent from the product.

12. A process according 'to claim 9 where Z is(3).

13. A process according to claim 11 wherein all R groups are alkoxy of 1to 4 carbon atoms.

14. A process according to claim 9 which is carried out continuously.

15. A process according to claim 11 which is carried out continuously.

16. A process of preparing a compound having the formula ZalkS alkZ, inwhich Z is (3) wherein R is alkyl of 1 to 4 carbon atoms or phenyl and Ris alkoxy of 1 to 8 carbon atoms, cycloalkoxy with 5 to 8 carbon atomsor alkylmercapto with 1 to 8 carbon atoms, alk is a divalent hydrocarbonof 1 to 18 carbon atoms comprising reacting a compound of the formulaZalk-SH with an oxidizing agent.

17. A process according to claim 16 wherein the oxidizing agent isselected from the group consisting of oxygen, nitric oxide, sulfurylchloride, dialkyl sulfoxide, halogen of atomic weight 35 to 127.

18. A process according to claim 17 wherein the oxidizing agent is ahalogen of atomic weight 80 to 127, sulfuryl chloride or dialkylsulfoxide of the formula R SOR where R and R are alkyl of 1 to 6 carbonatoms.

19. A process according to claim 18 wherein the oxidizing agent is R SOR20. A process according to claim 19 wherein the dialkyl sulfoxide isused in excess and the excess is employed as a solvent.

21. A process according to claim 20 wherein R and R are both methyl.

22. A process according to claim 17 carried out in the presence of asolvent and wherein the solvent is separated from the product.

23. A process according to claim 19 wherein Z is (3).

24. A process according to claim 23 wherein all R groups are alkoxy of 1to 4 carbon atoms.

25. A process according to claim 16 wherein Z is (3) and all R groupsare alkoxy of 1 to 4 carbon atoms.

26. A process according to claim 16 which is carried out continuously.

27. A process according to claim 22 which is carried out continuously.

28. A process according to claim 1 comprising reacting a compound of theformula Zalkhal wherein hal is a halogen of atomic weight 35 to 127 andis in the beta position to the silicon atom with a compound of theformula Me s, where Me is ammonium or an alkali metal and alk has atleast 2 carbon atoms.

29. A process according to claim 28 wherein Z is (3).

30. A process according to claim 29 wherein all R groups are alkoxy of 1to 4 carbon atoms.

31. A process according to claim 30 wherein alk is ethylene.

32. A process according to claim 28 which is carried out continuously.

33. A process according to claim 29 wherein alk is 2)3- References CitedUNITED STATES PATENTS 3,284,466 11/1966 Rosenthal 260-4482 N X 3,317,4615/1967 Plueddemann 260-448.2 N X 3,530,160 9/1970 Gardner et a1.260448.2 X

3,768,537 10/1973 Hess et a1. 260448.8 R N X DANIEL E. WYMAN, PrimaryExaminer P. F. SHAVER, Assistant Examiner US. Cl. X.R.

106308 Q; l52-330; 2604'1.5 A, 448.2 N, 448.8 R, 765, 766

1. A PROCESS OF PREPARIG A COMPOUND HAVING THE FORMULA Z-ALK-SN-ALK-Z,IN WHICH Z IS -SI(-R1)2-R2, -SI(-R2)2-R1, OR -SI(-R2)3 WHEREIN R1 ISALKYL OF 1 TO 4 CARBON ATOMS OR PHENYL AND R2 IS ALKOXY OF 1 TO 8 CARBONATOMS, CYCLOALKOXY WITH 5 TO 8 CARBON ATOMS OR ALKYLMERCAPTO WITH 1 TO 8CARBON ATOMS, ALK IS A DIVALENT HYDROCARBON OF 1 TO 18 CARBON ATOMS ANDN IS AN INTEGER OF 2 TO 6 COMPRISING REACTING A COMPOUND OF THE FORMULAZ-ALK-HAL WITH A COMPOUND OF THE FORMULA ME2SN WHERE ME IS AMMONIUM,ALKALI METAL OR AN ALKALINE EARTH METAL AND HAL IS A HALOGEN OF ATOMICWEIGHT 35 TO 127